Wet: Raftable flows 7 days a week through Labor Day.

The South Fork of the American River water year forecast as of May 8, 2019: Wet

The May Water Supply Forecast Report for 2019 was released Wednesday May 8th at 11:37 AM, with the final Water-Year forecast being Wet. Specifically it’s forecasting the Full Natural Flow (FNF) of the American River below Folsom at 3.910 million acre-feet (MAF), with Wet being considered ≥ 3.5 MAF.

snow water equivalent for central California

This is in line with the April forecast. Decreasing the forecast slightly by 1% versus the April forecast of 3.950 MAF.

As of May 1st, Central California’s snow water content is now at 118% of the April 1st average, and thus 147% of normal. We’ve seen 2.647 MAF of Full Natural Flow already recorded at Folsom Lake through April.

The current forecast has an 80% probability range of 3.610-4.330 MAF, which leaves little chance of the final water year dropping to Above Normal (2.6-3.5 MAF). If it did become an Above Normal year, the minimum flows would not change until Mid-October when that final determination is made. Keep in mind though that our brains are terrible at truly understanding what 80% probability means. It’s better to consider that if this exact forecast played out over 10 different years, one of those years would fall below that range, and one of those years would increase to above that range, and the other eight would fall within the range.

campers rafting on the south fork of the american river - satan's cesspool

Guaranteed Minimum Flows

The May forecast will be used to determine minimum guaranteed flows from May 11 through Mid-October.


  • Monday-Friday: 1,500 cfs 9am-12pm
  • Saturday & Sunday: 1,750 cfs 7am-1pm
  • Minimum Flow: 500 cfs

Summer Flows – Sat May 25th through Mon September 2nd

  • Monday-Friday: 1,500 cfs 8am-12pm
  • Saturday & Sunday: 1,750 cfs 7am-1pm
  • Minimum Flow: June: 500 cfs | July 350 cfs | Aug: 300 cfs

September 3-30

  • Thursday and Friday: 1,300 cfs 9am-12pm
  • Saturday & Sunday: 1,500 cfs 9am-12pm
  • No guaranteed raftable flows Monday through Wednesday
  • Minimum Flow: 250 cfs

Forecasted based on Current Data

In October the actual flows will be summed up and used to determine the future minimum flow regimen

October 2019

  • Monday and Friday: 1,300 cfs 9am-12pm
  • Saturday & Sunday: 1,500 cfs 9am-12pm
  • No guaranteed raftable flows Tuesday through Thursday
  • Minimum Flow: 250 cfs

 November 2019 through early February 2020

  • Saturday & Sunday: 1,500 cfs 9am-12pm
  • No guaranteed raftable flows Monday through Friday
  • Minimum Flow: 250 cfs

The actual water year should be calculated around October 8th, with it taking effect 3 days after issuance.

Snow water content graph for Central California

Extra Details for Geeks

Related Links and References

About the Forecasts

  • Forecasts are issued February through May around the 2nd Tuesday or the 8th of each month. They take effect 3 days after being released.
  • The final forecast is issued in May, and is used to determine the flow schedule through October.
  • The final (actual) water year report is released in October and is used to determine flows for November until 3 days after the February forecast is released.
  • While some bias might slip in, as much as possible the above information is purely based on the forecasts and not based on gut, intuition, or predictions.

As new forecast are released, this page will be kept as an archive of previous forecasts. For the most current forecast, or to view previous forecasts, please view our archive of water year forecasts here.